1. Technical Field of the Invention
This application relates to displays within scopes used for aiming rifles, pistols, and other projectile delivery systems. It especially relates to determining range-to-target values, providing range and windage-corrected aiming points, up-hill and down-hill, altitude, barometric pressure, barrel temperature and the other various affects commonly grouped as external ballistics and coordinating team firing activities.
2. Background of the Invention
Apparatuses for aiming of guns for sporting, competition, law enforcement, and military purposes are well known and wide spread. A very common aiming devices is known as a “scope”, which may be mounted to a variety of guns and weapons, including but not limited to rifles and pistols. Some scopes include a fixed magnification, or a variable magnification (zoom) feature.
However, due to certain forces on projectiles while in flight after the gun or weapon system has shot or launched the projectile, aiming and predicting accurately the point of impact of a projectile is more difficult than just determining a straight “line of sight” from the muzzle of the gun to a target. Projectiles are diverted from straight flight by a number of factors, including but not limited to, wind resistance, cross-wind vectors, and gravity. As such, ballistic paths within the Earth's atmosphere are often modeled simply as pseudo-parabolic vertical paths having a constant horizontal offset vector according to an average or mean cross wind speed.
Beginning shooters do not recognize the problem, but advanced and precision shooters, however, agree that such a simplification is unreliable for humane harvest of sentient animals or critical situations, such as hostage rescue team snipers, and for long range missions, such as military snipers. In these situations, variations in altitude, humidity, barometric pressure, cartridge chemicals, weight of projectile, and shape of projectile have considerable effect. Many competitive long range shooters, for example, “reload” their own shells to ensure uniformity of the chemical and hydration mixtures in each shell and the volume variation by manufacture, and they often resort to many idiocyncratic variations such as polishing their projectiles to ensure uniformity in projectile shape and wind resistance.
To address a very broad range of shooting applications, from small game to large game, short range to long range, from civilian to military, industry has responded by developing approximately 1500 different calibers, bullet shapes, and cartridge designs.
Because a projectile will drop a significant amount during such a long range trajectory, range estimation or measurement remains an important task or skill of the shooter. Further, selection of the proper “load” (e.g. caliber, bullet shape, bullet weight, etc.) is also critical to achieving accurate shot placement. The two factors are interrelated and co-dependent trajectory shape and load characteristics.
To accurately measure range-to-target values in long range applications, many shooters utilize electronic means, such as a laser or radar-based range finder. In certain scenarios, however, use of a range finding device which emits a “scatter” of signal can be dangerous and contraindicated. For example, such scatter can be detected, and the source pinpointed, by many military countermeasures. So, use of a laser range finder in a covert application on a battlefield may result in revealing the location of personnel.
Some range measuring techniques using markings on reticles in scopes have been developed. For example, the widely-used “Mil-Dot” reticle can be used to determine ranges by performing certain calculations relative to the graticule marks in the scope. But, these techniques remain math-intensive, are extremely distracting to the essential psychopsysiological performance state required for a successful shot, and are not conducive to practice by shooters of limited math skills or education. Additionally, some research shows that a human's math skills are diminished during times of intense stress, while other mental skills are increased, such as visual acuity. This shift of available mental faculties may temporarily disable a trained shooter from performing range calculations at the very time he or she may need them most.
In a different, but related problem, training of users of scope-equipped guns remains difficult because a coach is unable to see in real-time what the shooter is seeing. So, the coach is relegated to using diagrams and verbal descriptions to convey to the shooting student what the “sight picture” (e.g. the view of the target through the scope”) should look like, including any offsets (e.g. “holds” for bullet drop, windage, etc.).
In a similar application, teams of shooters, such as military sniper teams and hostage rescue teams, often are required to coordinate and assign targets. Coordination and command is usually performed by a centralized authority, but again, the central authority is unable to actually see what the team members can see via their scopes. So, the central authority must rely upon descriptions from the team members to make critical, sometimes life-or-death, decisions based upon these descriptions.
Therefore, there exists a need in the art for a means to provide quick and accurate range determinations when using a scope-equipped gun or weapon without relying upon mathematical or computational skills of the user. Specifically expert shooters understand the essential nature of never taking your eyes off the target once the target is acquired. There further exists a need in the art to share visual information from scopes of members shooting teams and groups to allow for improved training, coordination, and command.